How many people injured in Montserrat volcanic eruption?
19 people were killed, but most of the Southern part of Montserrat (where the volcano is) was evacuated.
A scientist can warn people of a volcanic eruption because of tremors that occur around the volcano, they can also record pressure thats building inside the volcano. Meaning they can warn people of a oncoming eruption and giving and exclusion zone. Also there are physical appearances such as smoke rising out of the volcano.